Artificial leather composition



- through the fibres.

' 4o stitute.

Patented Feb. 14, 1939 PATENT OFF-ICE 2,146,771 I ARTIFICIAL LEATHER COMPOSITION Horace A. Sheesley,

Tufide Products Corporation, a corporation of Maine Application October so, 1935, Serial No. 47,512

No Drawing.

9 Claims.

This invention relates to artificial leather compositions and more particularly to a composition comprising a mixture of fibres and a binder which can be economically and effectively used in the manufacture of articles heretofore generally made of good quality leather.

It has heretofore been proposed in the manufacture of artificial leather compositions, to mix liquid latex with the fibre either in the beater 10 or following the beater operation. The latex when so treated is inclined to coagulate and gum, resulting in an uneven dispersion of the binding material through the fibres when the sheet is formed.

It has also been proposed to form artificial leather compositions by providing multi-ply sheets of pulp tissue, each separate sheet being coated with a bindingmaterial before pressing the several sheets together. Another method :0 proposes to puncture sheetsby needle holes through which it has been attempted to force the latex binding material. The products formed by these known processes are not satisfactory since the binding medium is not uniformly dispersed in and through the fibres, with the result areas of weakness where it can be torn or broken under test or in service. The composition thus formed'also readily splits into layers which is most undesirable.

The vulcani'zing ingredients heretofore used in the composition also have a tendency to coagulate or congeal the binder before it'has an opportunity to become completely dispersed ir. and

latex-fibre leather substitutes as heretofore made, have a rubbery surface characteristic which is very unlike and immediately identifies it as a leather sub- I'he rubbery surface characteristic results from the concentration of excessive amounts of rubber solids by deposition upon the outer sur face of the material. The latex solids covering the surfaces of the composition become sticky,

45 under pressure and especially so indamp warm weather. This sticky surface characteristic is especially undesirable where the latex pulp material is to be used for the inner soles of shoes. The body weight on the foot exerts pressure on 50 these inner sole materials causing the feet or stockings to stick to the latex coating with resulting discomfort to the wearer. This sticlw surface characteristic is also undesirable in other articles or leather products as will beevident-to it those skilled in the art.

the superimposed tissue v that the material presentsthe surface of real leather Portland, Maine, assignor to Portland, Maine,-

Fibre-latex composition materials heretofore manufactured lack breathing qualities and are inclined to sweat-the feet of the wearer. Such compositions also have a tendency to 'peel' or rub off at the surface; leaving exposed unbound 5 fibres beneath, which in turn will rub off even more rapidly. This further characteristic makes fibre-latex composition materials as heretofore manufactured undesirable for inner soles, causing discomfort to the foot and undue wear on 10 the hose. Washing will not remove latex deposited on clothing or hosiery and for this reason latex pulp compositions heretofore manufactured have not found a ready use where the composition would come into frictional contact with 15 clothing or other washable fabrics.

An object of this invention is to provide an improved artificial leather composition which is strong, flexible and durable, which-will not readily split, crack, tear or break, which is comfortable to the wearer and remarkably adapted for the inner soles of shoes, which has the feel of genuine leather, which is inexpensive to manufacture, and which is remarkably adapted for many uses where fore been used.

Another object of this invention is to provide an artificial leather composition in which the fibres are felted and interlaced andthoroughly impregnated and homogeneously saturated with an improved binder, producing a material which is remarkably adapted for uses where genuine leather has heretofore been used.

Another object of this invention is to provide an improved process for manufacturing artificial leather compositions of the type herein described.

Another object of t s invention isto provide a binding solution for fibrous materials which can be easily and quickly applied to the fibrous material, which will thoroughly penetrate the 40 fibrous layer homogeneously and completely coat the individual fibres so as to form a homogeneous bond between the fibres.

' Another object of this invention is to provide. abinding solution having a latex component which will quickly and thoroughly penetrate a fibre mass, and which will thereafter quickly and economically expel the liquid component'of the solution and leave the solid binding mate- /rial evenly and thoroughly dispersed through the felted mass and inseparably united'to the fibres.

Other objects of this invention apparent as the disclosure proceeds.

The fibres forming a part of my improved will become genuine leather has heretothe addition of from artificial leather composition may comprise either cotton, linen, sisal, hennequin, hemp, and wood pulp fibres or a mixture of one or more of these. The well known varieties of wood pulp, such as Mitscherlich (sulphite) pulp, soda pulp, bleached sulphite pulp, sulphate (Kraft) pulp, may all be used. Old'rope and rag pulp also make an excellent material if the fibres still retain their normal tensile strength. It is, of course, necessary to beat and wash the rope or rag fibre material so as to remove all dirt and decayed fibres. It is evident that the stronger and tougher the fibre used the tougher and stronger will be the finished materia.

The binder with which the fibres are saturated preferably contains liquid latex as an ingredient. A high grade glue may be added to the liquid latex along with asmall amount of ammonia and formaldehyde, and a highly volatile organic liquid.

Glue of the blood albumin type is preferablyused but fish glues, hide glues, egg albumin, and other fat-free animal glues may also be used. Casein glue may be used, but it is not usually recommended due to the fact that it has a tendency to decompose in warm and moist weather. The compound should be free from zinc oxide which unfavorably affects the desired binding action of the latex or glue constituents.

The volatile organic liquids preferably used contain alcohol as the principal constituent. A liquid should be selected which is highly volatile, which will readily escape from the fibres and which will preferably aid in removing the less volatile liquid materials, such as water, from the composition during manufacture. A very satisfactory volatile liquid has been made from approximately to ethyl alcohol and approximately 10% of a mixture of methyl alcohol, acetone, ethyl acetate and aviation gasoline. The cheaper alcohols, such as wood alcohol or grain alcohol, preferably 170 proof, and upwards, can be used.

A small amount of liquid ammonia is added to stabilize the latex in solution and prevent a premature precipitation of the latex solids. A small amount of formaldehyde may also be added to assist in tanning the glue and prevent odors from the resultant product.

By way 'of example, the following formula has been found satisfactory for the purpose of this invention. To 8 pounds of liquid latex of good commercial grade is added 6 pounds of blood albumin glue which comprises approximately 1 pound of solid blood albumin and 5 pounds of water. The quantities above referred to are representative and of course will vary within fairly wide limits since liquid latex from various sources may vary in amount of solid constituents and various sources of blood glue also vary in water absorbtive qualities. A liquid latex containing approximately 40% rubber solids provides a desirable material. Sufficient water should be added to the solid blood albumin to reduce the same to a soft but non-flowing gel.

For blending purposes approximately to 2 pounds of a readily volatile liquid comprising a major portion of ethyl alcohol is added. The escape of the liquid constituents of the binder from the fibres may be facilitated by increasing the quantity of. alcohol added. The proportion of aqueous ammonia which is added will depend upon the amount of ammonia contained in the commercial liquid latex. As a general rule, however, most commercial grades of latex willrequire 1/ to 2 pounds of liquid ammonia to every 8 pounds of latex. Approximately ounce of formaldehyde added to the above constituents is suflicient to remove any odors from the material and exert the desired tanning and hardening action on the blood albumin glue. A binder material containing approximately the above proportion of ingredients is liquid and free flowing and can be readily incorporated into the fibrous mass to homogeneously coat the fibres and bind them into a solid mass.

In summarizing the effective formula above referred to the binder may contain approximately 18 to 22% rubber solids from latex, 4 to 7% of blood albumin giving a solid constituent of approximately 25%, a liquid constituent of '70 to 74%, and a gaseous constituent of 1 to 4%. The normally liquid and gaseous constituents would comprise approximately '60 to 65% water, 6 to 8% ethyl alcohol (which might also contain approximately 1% or less of methyl alcohol), ethyl acetate and aviation gasoline, together with approximately to 1% of. formaldehyde and from '1 to 3% ammonia.

The above formula is given by way of example only. The amount of liquid latex used may vary within wide limits depending upon the type of material desired. A strong, tough and fiexible material results when liquid latex in the approximate proportions above given are used. If a considerable increase in liquid latex is made the material will begin to have a rubbery feel and will be inclined to sweat the feet when used as an inner'sole.

Commercial latex varies in solid latex constituents anywheres from 25 to 60%. Since the solid constituent is the important component it is always desirable to test each batch of latex for rubber solids before combining the same into the mixture. Different types of albumin blood glue will also absorb different quantities of water varying from 1 part dry glue to 4 to 7 parts water, the source of the albumin which Suiiicient water should be added to the dry glue to produce a. soft but non-flowing gel. A composition comprising approximately 1 part latex solid to 1 part glue gel will produce a material which possesses hardness and considerable stiffness. A composition containing approximately 4 parts latex solid to 1 part gluegel makes an excellent leather substi-. tute, highly adaptable for inner soles and quarter linings for shoes. The percentages used may thus be varied from approximately 1 part latex solid to 1 part glue gel (producing a relatively hard stiff material) to approximately 9 parts latex solids to 1 part glue gel (producing a highly flexible tough and strong material). From 2 to 20% of highly volatile liquids such as alcohol may be used, depending upon the hardening and drying speed desired.

In carrying out the process, the proper proportions of liquid latex and albumin glue gel is placed in an agitator or mixer and slowly but thoroughly mixed for approximately thirty minutes. The proper amount of ammonia should also be added to prevent the latex from congealing during the mixing. When the mixing has been completed, the mixture flows from the agitator to a paint mill of well known construction, where the materials are further mixed and the ingredients thoroughly dispersed. From the paint mill the material flows to an air-tight compression tank where air pressure from 40' to L pounds per-square inch is applied. The material 75 ing material.

in the compression tank is connectedby suitable flexible hose to a spray gun which drives the liquid binder into a loosely felted web of fibres to thoroughly impregnate, and saturate the fibres and provide a uniform homogeneous bond therebetween. V

It is well known that exert a setting, cooking or congealing action on albumin glues and also operate tocongeal the latex, It is of the utmost importance that no congealing action of the latex or glue gel mixture takes place until the fibres have been thoroughly impregnated and saturated with the bind- I overcome this congealing action by feeding the alcohol or other highly volatile constituent into the pressure feed line leading to the nozzles or into the compression tank as appears most convenient and desirable. The alcohol mixes with the latex-glue gel material as it passes through the spray gun and it is therefore given no appreciable time or opportunity to effect congealing action of the latex or glue gel until the fibres have been uniformly coated therewith. The formaldehyde, which also exerts a certain hardening or tanning action on the gelatine, is also preferably fed into the pressure stream where it has no opportunity to effect theglue gel until the fibres have been thoroughly impregnated.

The fibres comprising cotton, linen, hemp or wood pulp fibres or a mixture these, are fed in dry condition into a carding or shredding machine. The shredder acts to thoroughly mingle and intertw' e the various fibres in a loose felted mass. The loose felted mass of fibres is evenly distributed in a layer of the proper thickness and then subjected to the action of the spray guns which project the liquid binder into the loosely felted mass of dry fibres, until all the fibres, have been uniformly impregnated and coated with the liquid binder. An initial compacting pressure is then exerted on the sprayed mass of fibres as the saturated web is carried along on a moving belt. The alcohol or highly' volatile material quickly escapes from the fibres by evaporation and carries with it a considerable quantity of aqueous material contained therein. fi efore escaping, however, the alcohol as Well as the formaldehyde exerts a setting and hardening action on the latex solids and glue binders with the result that the saturated web quickly assumes a self-sustaining tensile strength.

When the saturated web has assumed an initial set a powdered material is dusted uniformly over the. surfaces of'the web to give the finished material the desired leathery feel and remove surface stickiness. surfacing material, although other powdered materials, either of animal, vegetable or earthy origin may be used. After passing through the duster applicator the web moves into a drying tunnel where it is heated to approximately 212 F. and upwards to 250 F. more, or fiss. The greater proportion of volatile liquid co stituents, particularly water, are driven 01f and evaporated from the felted web in the drying tunnel. To hasten the drying action, the drying tunnel may be reduced to a partial vacuum by means of vac uum pumps and suitable means, such as condensing apparatus, may be provided to recover the volatile material, such as alcohol, used in the process.

During the travel of the webbing through the tunnel dryer or immediately following its travel through the tunnel dryer, the webbing may be passed through one or more sets of compression concentrated alcohols of one more 'the fibre material to 70 or 80%.

Wood fiourprovides a satisfactory rollers to compact and compress the material together into a' homogeneous sheet. The sheet then passes through dryers preferably of the festoon type and the sheet run through further compression rollers or a leathering machine positioned either within or outside the festoon dryer. The finished artificial leather composition can then be rolled into a roll or cut into strips of the desired size.

A layer of carded felted fibres approximately two inches in thickness will reduce down to a completed artificial leather composition approximately of an inch thick: The looseness of the felted layer through which the binding solution is sprayed can thus be readily understood. In addition, the felted condition of the fibrous constituent gives a finished material of uniform strength in all directions.

An unusually tough and strong material having the desirable characteristics of genuine leather may be formed by combining approximately one gallon of the liquid latex glue binder with approximately 5 pounds of wood pulp. The finishedartificial leather product preferably contains from 50 to 65% substantially dry pulp'and from to solid binder material. These proportions of course can be varied to give materials having a more fibre-like composition binder constituent to 20 or 30% and increasing To make a material having more rubber-like characteristics the binder material can be increased to or of the total composition. If strength and toughness is not of prime importance, can be materially decreased and ponent proportionately increased product which is stiffer and yet porous and possesses ity or breathing of natural leather is thus readily simulated, in varying degrees, in the products of the present invention.

The albumin glue increases the resistance of the resultant product to water and heat and increases its firmness and hardness. The glue constituent appears to assist thorough penetration of the fibres and a completedispersion of the solid particles of the binder among the fibres. The volatile solvents, as above described also greatly assist in the driving off or removal of the water constituent, thus shortening the time for drying the glue comto produce a is strong and of the finished material and furthermore assists 0 making the product homogeneous. While the above binder compound fiows readily and appears to be even more liquid than the latex constituent, it neverthelesshas the unusual and desirable characteristic of drying out with greater rapidity thanmoves through the apparatus, effecting further saving in cost of manufacture. Thus a product which has superior qualities over artificial leather compositions heretofore made is produced at a great saving in cost. The product is especiallyadapted for shoe manufacture and particularly by reducing the a leathery feel. Respirabil-.

the liquid latex .inner soles. Actual tests of the material in use feet,

as inner soles have demonstrated that my artificial leather composition is comfortable to the substantially respirable and waterproof, prevents the entry of moisture through the shoe and yet does not draw the feet nor cause the feet to sweat or heat.

My artificial leather composition may be given a surface appearance closely resembling suede leather'by dusting suitably dyed ground cotton, hemp or sisal linters over the surface of the material. Highly desirable wall and floor coverings of great strength and wearing qualities can also be made by using rope or hemp fibres in the composition. The finished material may be made of any desired thickness ranging from two irons to twenty-four irons.

The invention further consists in the new and novel compositions and in the constituents as set forth in the specification and all equivalents thereof, including the new and useful arrangement and combination of steps in the process herein described and more particularly set forth in the claims annexed hereto.

What is claimed is: I

1. An artificial leather sheet material including a body portion comprising from 50 to of felted and compressed wood pulp fibres and a binder material for the fibers, said wood pulp fibres extending in all directions with no defined directional arrangement, the said binder material consisting of homogeneous dehydrated latex, and blood alubumin, tanned in situ.

A respirable artificial leather sheeting inclu'ding a homogeneous body portion comprising 50% and upwards of felted and compressed wood pulp fibers extending throughout the body portion in alidireotions, said unoriented fibers bein interbonded and joined in a tough mass of highsubstantiaily uniform tensile strength in all directions, the bonding material for the said sheeting comprising the solid residuant of a liquid fiowable mixture of latex, blood albumin glue and a tanning agent.

3. A respirable non-laminated artificial leather sheeting including a homogeneous body portion comprising 50-70% of compressed wood pulp fibers extending in all directions, said-fibers being interbonded and joined in a tough mass of high substantially uniform tensile strength in all directions, the bonding material for the said sheeting' comprising the solid residuant of a liquid fiowable mixture of latex, blood albumin glue and a tanning agent.

4; A respirable artificial leather sheeting including a homogeneous body portion of compressed wood pulp fibres extending in all direc-' tions, said fibers being interbonded and joined in a tough mass of substantially high tensile strength in all directions, the bonding material for the said sheeting comprising the solid residuum of a-liquid fiowable mixture of' latex,

blood albumin glue and a tanning agent, and a pulverulent surfacing of natural cellulosic materials incorporated on and in the surfaces of said sheeting. 1

5. A respirable artificial composition sheeting having a leathery finish including a homogeneous body portion of compr ssed natural cellulosic fibres-extendingin all directions, said fibers being interbonded and'joined in a tough mass of high substantially uniform tensile strength in all directions, the bonding material for the said sheeting comprising the solid residuum of a liquid fiowable mixture of latex, albumin glue and a tanning agent, and a pulverulent surfacing of natural cellulosic materials incorporated on and in the surfaces of said sheeting, the said cellulosic materials comprising dust of cellulosic fibres.

6. A respirable artificial composition sheeting having a leathery suede finish including a homogeneous body portion of compressed natural cellulosic fibres extending in all directions, said fibers being interbonded and joined in a tough mass of high substantially uniform tensile strength in all directions, the bonding material for the said sheeting comprising the solid residuum of a liquid fiowable mixture of latex, alubumin glue and a tanning agent, and a pulverulent surfacing of natural cellulosic mate: rials incorporated on and in the surfaces of said sheeting, the said cellulosic materials comprising dust of ground cotton linters.

"I. A respirable artificial composition sheeting having a leathery suede finish including a homogeneous body portion of compressed natural cellulosic ,fibres extending in all directions, said fibers being interbonded and joined in a tough mass of high substantially uniform tensile strength in all directions, the bonding material for the said sheeting comprising the solid residuum of a liquid fiowable mixture of latex, alubumin glue and a tanning agent, and a pulverulent surfacing of natural cellulosic materials incorporated on and in the surfaces of said sheeting, the said cellulosic materials comprising dust of ground hemp fibre.

8. A respirable artificial leather including approximately 60% of matted wood pulp fibers extending in all directions, each fibre being impregnated of the residuum of a mixture including approximately 30% rubber latex solids and 10% blood albumin glue tanned during the formation of the artificial leather in situ. I

9. An artificial leather including substantially 50 to 70% of matted wood pulp fibers extending in all directions, the fibres being severally impregnated and coated with a-mixture comprising approximately 20 to 40% approximately 6 to 15% albumin tanned during the formation of the artificial leather in situ.

HORACE A. S.

and coated with substantially 40%.

rubber latex solids and- 

